In general, a vehicle, such as an automobile, is provided with an airbag device for absorbing impact on an occupant by inflating and deploying an airbag in a vehicle in an emergency, such as a collision or a sudden deceleration. In general, such an airbag device includes an airbag and an inflator. The airbag is normally folded and accommodated in a structural member of the vehicle, and is inflated and deployed in an emergency. The inflator supplies gas to the airbag.
For example, in the case of a side airbag device, the airbag device is built in a seat back of a seat on which an occupant sits; and, at the time of a collision of a vehicle or a sudden deceleration, an airbag breaks through or pushes through the seat back, is released towards the front in a vehicle, and is quickly inflated and deployed at a location between an occupant and a door of the vehicle. Various structures of such an airbag have already been proposed (see PTL 1 to PTL 4).
For example, the airbag in PTL 1, instead of having a three-dimensional structure, has a structure in which inflation assisting means is formed at peripheral edge portions of a pair of panels of the airbag by forming a fold region that is folded into of an inflation region. Such inflation assisting means having a planar panel structure is capable of assisting the inflation in a vehicle lateral direction at a portion of the inflation region and partly increasing a deployment width.
The airbag in PTL 2 includes a substantially hermetically sealed space in an interior thereof as a result of folding and sewing one base cloth having a predetermined shape so as to bring together end portions of the entire periphery of the base cloth. According to such a structure, it is possible to make it unnecessary to perform an outer periphery stitching step and to reduce manufacturing costs.
The airbag in PTL 3 includes a tube that is disposed adjacent to an inflatable cushion and that is disposed at one of a bottom portion and rear portion so as to extend along the airbag before the cushion is completely inflated by an inflation gas. Such a structure makes it possible to supply gas to a cushion section after the tube is first completely inflated and to reduce impact on an occupant at what is called an out of position (position that is displaced from a standard seating position).
The airbag in PTL 4 includes a rear chamber, formed of a tube panel; a front chamber, formed of a cushion section; and a ventilation system including a ventilation opening and a blocking panel. The ventilation opening is disposed in the front chamber. The blocking panel is capable of covering and uncovering the ventilation opening. Such a structure makes it possible to discharge gas to the outside by causing the ventilation opening to be uncovered when the inflation of the front chamber is prevented, and to reduce impact on an occupant at what is called an out of position.